1. Field of the Invention
The invention relates to P.E.T. bottle conveyors and more particularly relates to a bottle conveyor which propels bottles by forcing air onto bottles beneath their neck rings, and to an extremely thin guide which may be used in such a bottle conveyor.
2. Discussion of Related Art
Conveyors are well known for transporting plastic bottles or the like from one location to another, e.g., in a bottling plant. The bottles typically include an enlarged body, an annular neck ring, and a neck extending from the neck ring to the body. The typical conveyor includes a neck guide which supports the neck rings of the bottles as air is forced onto the bottles from directional slots formed in plenums located on opposite sides of the bottles, thereby propelling bottles along the neck guide. Such neck guides typically include lips formed from a UHMW (Ultra High Molecular Weight) plastic, polished stainless steel, or coated stainless steel. These conventional lips exhibit significant strength and/or shape limitations and thus must engage a relatively large area of the neck ring and/or must be relatively thick and extend a substantial distance beneath the neck ring. Since shipping and aesthetic considerations have led bottlers and the like to employ bottles with small neck rings and with very short necks, traditional thick neck guides are proving unacceptable for the conveyance of some bottles.
The traditional relatively thick neck guide also imposes limitations on plenum slot placement. That is, the traditional guide takes up substantial space near the top of the bottle such that the plenum slots must be located beneath the neck. Such slots are thus incapable of directing conveying air directly onto the transition area between the neck ring and neck of the bottle, and in fact often direct air onto the lower portion of the body of the bottle. Air as thus applied imposes little or no lift on the bottle and thus does not reduce the friction between the neck guide and the neck ring. This necessarily increases the volume of air required for conveyance. Moreover, directing air onto the lower rather than the upper portion of the bottle tends to impose substantial pivoting or rocking forces at the interface between the neck ring and the neck guide which at best increase drag and which may render conveyance impossible. Such rocking forces are offset in the typical prior art conveyor by employing a dual plenum configuration in which air is imposed on both sides of the bottle by opposed plenums. The lateral forces imposed by these dual airstreams tend to offset one another so that rocking forces are reduced. Such a dual plenum configuration, however, requires additional equipment and floor space and also requires more air than would otherwise be required for conveyance.